1. Field of the Invention:
The invention relates to an apparatus for the packaging of products such as mineral wool felts.
2. Background of the Related Art:
A conventional way of packaging a felt strip consists of rolling the felt up onto itself and compressing it. Thus, cylindrical rolls are formed which are wrapped and held in by a sheet of paper or polymer material.
To form compressed felt rolls and wrap them with a sheet to form a unitary package, it is conventional practice to use a machine such as that which is the subject of U.S. Pat. No. 4,583,697 or other similar machines. In these machines, the felt is rolled up on itself within a defined space. In the case of the aforesaid Patent , this space is defined by two conveyor belts and a compression roller. In other machines, the confined space is constituted by a plurality of rollers. In all cases, the rollers and conveyors are caused to move so as to entrain the felt into the space which they bound while at the same time imparting a certain compression to the roll being formed.
Compression of the felt in the roll is provided during the regular rolling-up of each turn. In some way or another, it is essential to keep the strip of felt forming the roll properly tensioned throughtout the entire operation. Otherwise, even if the felt is kept compressed within the restricted space, the roll would tend to resume its volume once the compression was relaxed.
In order to keep the felt properly tensioned during each of these turns, it is necessary to precisely regulate the speeds of the elements defining the space in which the roll is formed and in particular that of the final roller with which the felt is in contact. It is this final roller which makes it possible to properly regulate the "tension" which is exerted on the felt while it is being compressed. Following contact with this roller, the conditions of rolling-up and of compression which result therefrom are no longer open to change. The position of the turns of the roll in relation to one another is finally established. For this reason, the peripheral speed of this roller is often maintained slightly higher than that of the other rollers or conveyors constituting the rolling or winding machine.
In the ensuing description, reference is made to a machine of the type comprising two conveyors and one compression roller for the part in which the felt is rolled up. The same considerations may apply to other machines, particularly to those which only comprise rollers.
When using these rolling-up machines, certain difficulties have been encountered in maintaining satisfactory conditions. The roll of formed felt does not, for example, exhibit the desired compression characteristics, its diameter may be greater than that envisaged or the rolling-up action is irregular, the end faces of the roll form cones, to mention only the main difficulties.
Such difficulties have an effect on the resulting packages. It is not possible to stack the rolls on end faces unless these are flat. Once the required dimensions have been exceeded, the completed bundles no longer have the right outline to be loaded on railway wagons or trailers.
Although it is possible, to a certain extent, to compensate for defective operation of the apparatus, at least with regard to the dimensions, such a correction is often achieved only to the detriment of the quality of the rolling-up operation. Indeed, U.S. Pat. No. 4,583,697 has stated the importance of the way in which the rolling-up is carried out, its effect on the qualities of the felt when it is used later on and that as far as possible the compression exerted over the entire length of the felt constituting the roll should be properly monitored. A poor rollingup, in compression with that which it is desired to achieve, ordinarily leads to a badly distributed compression (generally over compression at the outset) which adversely affects the felt's later resumption of thickness and hence its insulating properties.